The present invention relates to a vehicle transfer case gear shift fork assembly.
A Society of Automotive Engineers, Inc. Technical Paper Series No. 80002 entitled, "Internal Transfer Case Controls for Four Wheel Drive Vehicles", dated Feb. 25, 1980 by Gamble E. Huffaker discloses a mode shift arrangement for a transfer case. This transfer case is commercially available from the New Process Gear Corporation, a subsidiary of Chrysler Corporation, and carries the designation NPG Model 208.
In the Model 208 arrangement a first clutch spring encircles a shaft supporting a sliding clutch to force the clutch forward to engage clutching teeth. A second fork spring encircles the shift rail such that the shift is easily made against the spring force. When a torque reversal is obtained releasing the clutch load, the fork and mode sliding clutch are moved rearward out of engagement by their associated springs. In this arrangement the fork spring must be stronger than the clutch spring as the clutch spring is compressed in its four-wheel drive shift position. It is an object of the present invention to provide a dual fork spring arrangement wherein the relative force of each fork spring may be neglected while alternately shifting against each of their forces in opposite directions.